1. Field of the Invention
The present invention relates to an image sensor, and more particularly, to an image sensor capable of measuring illumination, proximity and color temperature, which can measure current illumination, proximity to an object and color temperature of the object by using variation of an output voltage value according to the existence or absence of infrared and visible ray with a wavelength of a specific band.
2. Description of the Related Art
In general, an image sensor using a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) has an absorption band of 40 nm to 1100 nm. Furthermore, visible ray normally has a wavelength of 380 nm to 650 nm and infrared has a wavelength of 650 nm to 1100 nm. It is general that such an image sensor uses an infrared (IR) cut-off filter, which allows light with a wavelength of 650 nm or less to pass therethrough and cuts off light (i.e., infrared) with a wavelength of 650 nm or more, in order to detect and display colors the same as those perceived by the human eye.
According to the prior art, light in an infrared area is used as a light source in order to acquire an image by photographing an environment (e.g., a monitoring camera) with less external light, that is, a night environment, a sealed space after an electric light is turned off and the like, by using such an image sensor. In order to use the light in the infrared area as the light source according to an external environment as described above, when light from an external light source is sufficient, the light in the infrared area is cut off by the IR cut-off filter to improve image quality. When the light in the infrared area is used as the light source for lack of the light from the external light source, the IR cut-off filter is not used to allow the light in the infrared area to reach the image sensor.
Therefore, a moving unit capable of changing the position of the IR cut-off filter according to the existence or absence of the external light source is essentially required for a system using the image sensor. Installation of the moving unit that mechanically moves the IR cut-off filter may increase the size and manufacturing cost of a monitoring camera and the like.
Furthermore, an infrared light emitting diode used for a conventional image sensor has been generally limited only to a function as a light source for acquiring an image in a dark environment.
Recently, there are increased demands for a proximity function capable of automatically controlling a mobile apparatus according to the distance between a user and the mobile apparatus in the case of using the mobile apparatus such as a digital camera or a cell phone, and an electronic apparatus. In this regard, when the distance between the user and the mobile apparatus is measured and the user is located near the mobile apparatus based on the distance information, the proximity function has been proposed to reduce power consumption by automatically cutting off power supplied to a backlight unit (BLU) provided in a liquid crystal window, or to prevent an abnormal operation by automatically stopping the operation of a touch sensor.
In order to realize such a proximity function according to the related art, a proximity sensor separately manufactured using a light emitting diode (LED) and a light receiving element has been installed in a mobile apparatus, an electronic apparatus and the like for use.
However, when the separate proximity sensor is installed as described above, the size of the mobile apparatus, the electronic apparatus and the like is increased, resulting in going against the recent technology trend toward performance of a plurality of functions through miniaturization of products, and an increase in the manufacturing cost for installing the separate proximity sensor.
Moreover, an entire image pixel is required to measure the color sense or color temperature of an object, resulting in an increase in power consumption.